You don't see the whole situation.
When the X-country is made an outcast in the world economy, this is a blow to the X-country.
When SEVERAL countries become pariahs, they have no choice. They unite in order to survive.
If these few countries are both territorially and materially a SIGNIFICANT part of the entire planet, then they will survive on THEIR terms.
Now it’s probably worth thinking about who created the conditions for 1 - the emergence of rogue countries, 2 - their unification